Due to large-scale electrolytic bath's higher requirements for the quality of the pre-baked anode and control of the anode production cost, most enterprises use pot furnaces to calcine petroleum coke. The advantages of pot furnaces in calcined coke quality and yield become more evident. This is mainly because during calcination in the pot furnace the petroleum coke is heated indirectly by high temperature gas, has a high calcination temperature and has a long calcination time. The calcination temperature can reach 1250° C.˜1350 ° C.; the discharge speed is generally about 100 kg/h; the true density of the calcined coke can reach about 2.08˜2.10 g/cm3; and carbon burning loss during the calcination is only 3˜4%.
However, with the decline in the quality of petroleum coke products of petrochemical enterprises, as well as purchase of low-cost high-sulfur coke in great amounts by enterprises to reduce the production cost of calcined coke, the sulfur content in the petroleum coke calcined in pot furnaces increases significantly, which brings about a series of problems:
1) Sulfur in petroleum coke corrodes the silicon brick of the body of the pot furnace in the high temperature calcination process, resulting in reduced service life of the silicon brick and thus a direct reduction in the service life of the pot furnace. The service life of pot furnaces could reach 10 years in the past, but with the use of high-sulfur coke, the service life decreases directly to 3 to 4 years; and
2) Sulfur which precipitates during high temperature calcination enters the flue gas and generates SO2, leading to a sharp increase in the concentration of SO2 in the flue gas, even up to 4000˜6000 mg/Nm3 in some cases. This not only reduces the service life of the smoke exhaust system equipment, but also greatly increases the difficulty and cost of desulfurization.